Supported liquid membrane transport studies on Am(III), Pu(IV), U(VI) and Sr(II) using irradiated TODGA

Transport behaviour of actinides viz. Am(3+), Pu(4+) and UO(2)(2+) was investigated from nitric acid feed conditions using PTFE (polytetrafluoroethylene) flat sheet supported liquid membranes (SLM) containing an irradiated solvent system comprising of N,N,N',N'-tetra-n-octyldiglycolamide (TODGA) as the carrier extractant and N,N-di-n-hexyloctanamide (DHOA) as the phase modifier. The present studies were carried out in order to understand the effect of irradiation on the long term reusability of the SLM and the decontamination behaviour in the absorbed dose range of 0-100 MRad. The studies using irradiated carrier included those with irradiated TODGA without any phase modifier and with 0.1M as well as 0.5M DHOA as the phase modifier. Transport behaviour of all the metal ions were found to be seriously affected with increasing radiation dose which was reflected in the decreasing percentage transport (%T) as well as permeability co-efficient (P) values. Though Sr(II) transport was quite significant with all the three unirradiated solvent systems, it was surprisingly low (<5%) when solvents exposed to 100 MRad dose were used in the SLM. Separation factors (S.F.) of the actinides over Sr(II) were calculated and were found to increase at higher radiation doses suggesting possibility of getting better decontamination on prolonged use of the supported liquid membrane system.

Solvent extraction behaviour of some fission product elements withN,N-dihexyl octanamide and tri-n-butyl phosphate under simulated PUREX process conditions

Extraction behaviour of some fission product contaminants like Zr(IV), RuNO(III), La(III), Ce(III) and Nd(III) with 1.1 M solutions ofN,N-dihexyl octanamide (DHOA) and tri-n-butyl phosphate (TBP) inn-dodecane from nitric acid medium has been investigated under conditions prevailing in the PUREX process. Results of the study reveal that the extraction of Zr(IV), La(III), Ce(III) and Nd(III) with 1.1 M DHOA is significantly lower than that of TBP. However, the extraction of RuNO(III) with DHOA is of the same order as that with TBP. The influence of uranium(VI) saturation of the organic phase on the extraction of Zr(IV) and RuNO(III) is evaluated. The effect of degradation products of DHOA (caprylic acid/n-dihexylamine) and TBP (di-n-butyl phosphoric acid) on the extraction of Zr(IV) is also examined. The study indicates the innocuous nature of the degradation products of DHOA towards the extraction of Zr(IV) under the PUREX process conditions. This is unlike the degradation products of TBP, the presence of which produce noticeable increase in the extraction of Zr(IV).